LOS ANGELES — In the middle of the rainbowy revelers at the pride parade in West Hollywood, Jeremy Stacy was questioned: Are you really bisexual?

“One guy came up to me and said, ‘You’re really gay,’ ” said Stacy, who was standing under a sign reading, “Ask a Bisexual.”

“I told him I had a long line of ex-girlfriends who would vehemently disagree. And he said, ‘That doesn’t matter, because I know you’re gay.’ ”

Stacy had gotten the question before. From a friend who said anyone who had slept with men must be gay — even if he had also slept with women. From women who assumed he would cheat on them. From a boyfriend who insisted Stacy was really “bi now, gay later” — and dumped him when he countered he was “bi now, bi always.”

Such attitudes appear to have kept many bisexuals in the closet. At a time when gay rights have made stunning strides, and gays and lesbians have become far more willing to come out, the vast majority of bisexuals remains closeted, a Pew Research Center survey revealed last month.

Only 28 percent of bisexuals said most or all of the important people in their lives knew about their sexual orientation, compared to 71 percent of lesbians and 77 percent of gay men, Pew found. The numbers were especially small among bisexual men: Only 12 percent said they were out to that degree, compared to one-third of bisexual women who said the same.

Closeted bisexuals told the Los Angeles Times that they had avoided coming out because they didn’t want to deal with misconceptions that bisexuals were indecisive or incapable of monogamy — stereotypes that exist among straights, gays and lesbians alike.

The stereotypes make some reluctant to use the word, even after they come out. Laura McGinnis, communications director for the Trevor Project, an LGBT-youth suicide-prevention group, said she was 29 or 30 before she would readily share that she was bisexual or actively correct someone who thought otherwise.

“I hated the label because the assumption is that you’re sleeping around,” said McGinnis, now raising a child with her wife.

Such assumptions could make being out at work especially difficult: Only 11 percent of bisexual people polled by Pew said most of their closest co-workers knew about their sexual orientation, compared to 48 percent of gay men and 50 percent of lesbians.

Bisexuals were also less likely than gay men and lesbians to say their workplaces were accepting of them, Pew found. In a separate study published in the Journal of Bisexuality, half of bisexual people surveyed said their gay and straight co-workers misunderstood bisexuality.

“Bisexuals are thought to be confused, opportunistic and unable to make commitments — and those aren’t the kinds of things you want to see in an employee,” said Denise Penn, vice president of the American Institute of Bisexuality, a nonprofit that funds research.

LGBT community reacts

Inside the gay community, bisexual people are often seen as more privileged than gays and lesbians, able to duck discrimination by entering into straight relationships.

Far more bisexuals are in relationships with people of the opposite sex than the same sex, Pew found. They are less likely than gay men and lesbians to have weathered slurs or attacks, been rejected by friends or family or treated unfairly at work, its survey showed.

Yet researchers and activists say bisexuals face another set of frustrations, sometimes shunned by the gay and lesbian community and the straight world alike.

Bisexual women complain they are leered at by straight men and rejected by some lesbians as sexual “tourists” who will abandon them for men. Bisexual men, in turn, struggle to persuade men and women alike that they aren’t just gay men with one foot in the closet. Both are stereotyped as oversexed swingers who cannot be trusted.

“Women would say, ‘I don’t date your kind,’ ” said Mimi Hoang, who helped form bisexual groups in Los Angeles. Such reactions left her frustrated. “I had nothing against lesbians. I thought I could find camaraderie with people who were also sexual minorities.”

Bisexual activists lament the “B” is overlooked by LGBT organizations that provide little programming specifically for them. Pew found that bisexuals — especially men — were less likely to have belonged to such groups. More than half said they have only a few LGBT friends or none at all.

Researchers believe such isolation may have dire results. Some studies have found that bisexual people are at greater risk of emotional woes than people who are gay, lesbian or straight: Bisexual women are more likely to binge drink and suffer depression, a George Mason University study found.

A Kent State University study of bisexual women found that they were more likely than straight or lesbian women to harm themselves or endure suicidal thoughts. Other studies have also cited higher risks for bisexual men.

“I think these problems are coming from two places,” said Northwestern University human sexuality researcher Allen Rosenthal. “The absence of a bisexual community and the psychological stress of being in the closet.”

Activists say bisexuals have two closets — a straight and a gay one.

While a gay man might casually mention his husband, or a lesbian might out herself by talking about her girlfriend, bisexuals are often wrongly assumed to be straight or gay depending on whom they are with. Spelling out that they are bisexual can be misconstrued as rejecting a current partner or declaring themselves up for anything.

Not viewed as a phase

University of Utah research backs up the argument that bisexuality is not just a phase: Though 62 percent of gay men once identified as bisexual, nearly as many bisexual men — 56 percent — had once said they were gay, professor Lisa Diamond found. More women switched from calling themselves lesbian to calling themselves bisexual than vice versa.

Though surveys show bisexuals rival or exceed gays and lesbians in number, experts say there is still little known about bisexuals because studies often group them with gay men and lesbians.

While research lags, reality may already be changing: Younger people seem more at ease with bisexuality, adopting alternative labels such as “pansexual” or shrugging off labels completely, McGinnis said.

Northwestern University researcher Brian Mustanski said unlike earlier studies, his research showed bisexual youth were less likely to suffer mental disorders than gay and lesbian youth — a possible sign of growing acceptance of sexual fluidity.

But there’s still a long way to go, said Ellyn Ruthstrom, president of the Bisexual Resource Center in Boston.

In the middle of a pride parade, “I’ve had people shout out to me, ‘When are you going to come out?’ ” she said. “Excuse me? We’re marching in a pride parade. How out is that?”